Gulf svlphub



WILLIAM HOFFMAN KOBBE, OF NEW YORK 1,551,574. PATENT OFFICE.

, N. 2., ASSIGNOR r0 TEXAS GULF SULPHUR (JOllllIIANY QF IB AY CTTY, TEXAS, A CORPORATION OF TEXAS.

'METHO-D or mrnovme THE rnornn'rrns ,or SANDS'IONE AND THE rnonvo'r I rnnnnor.

No Drawing. Application filed ll prif28,

ToaZZ whom it may concern:

Be it known that I, WILLIAM H. Konmi, a citizen of the United States, residiryrg at. New York city, in the county of New ork, State of New York, have invented certain new and usefulImlprovements in Methods of Improving the roperties. of Sandstone and the Product Thereof; and I" do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. This invention relates to sandstone and has for its object the provision of a method of improving the properties of sandstone. Sandstone is an indurated sedimentary rock formed of coherent or cemented sand. There are many varieties of sandstone, such forexample as asphaltic sandstone, bluestone, brownstone, building sandstone, flagstone, and freestone. Throughout this specification and appended claims I intend to include in the term sandstone any indurated sedimentary rock formed of coherent or cemented sand. The present invention contemplates a method of improving the properties of sandstone to render it more suitable for its common uses, and moreover to adapt it for uses for which it has been heretofore unsuitable.

I have discovered that sandstone treated in accordance with the present invention possesses superior strength, increased dielectric strength, and other improved physical and chemical properties, such for example, as increased resistance to corrosion, and increased imperviousness to moisture. The' invention also contemplates an improved sandstone product.

' The invention involves-fimpre ating the pores or interstices'of the san stone with sulfur and permitting the sulfur; to congeal therein topbtain a hard impervious mass.

Although sulfur is a brittle relatively weak material,-nevertheless, when the pores or interstices of sandstone are impregnated with congealed sulfur, the strengthmfthe resulting product is from two or-three times reater than that of the original sandstone. T3y congealed sulfur, I mean sulfur which has solidified or congealed situin the interstices 'of' sandstone, the sulfur being initially introduced in a liquid or molten condition into the interstices.

1924. Serial No. 709,698.

Various methods may be employed for impregnating sandstone with sulfur. 'In order to secure a most satisfactory impregnation of the sandstone with the sulfur, the pores or interstices of the Sandstone must be freed of gases to permit filling of the pores with sulfur. l/Vhen it is desired toimp'reg nate relatively smal-lobjects of sandstone they may be introduced, either with or without preheating, into a bath of molten sul fur at a temperatureof about 120 C. at which temperature the sulfur is a relatively thin liquid. The sandstone objectsshould be completely submerged in the bath, and if necessary means should be provided. for

holding them below the surface of the sulfur. The temperature of the bath should be raised toexpel the gases from the pores of the sandstone. F or this purpose the temperature of the sulfur may be increased to about 220 C. at' which temperature the sulfur becomes viscous. This causes the heat of the bath to penetrate well into the objects and completely expel the air or other gases from the r pores. After the gases have been thoroughly expelled, as indicated by the reduction in the amount of gas bubbles com ing to the surface of the bath, the temperature of the bath may be lowered until the sulfur again reachesthe thin liquid stage. The gases now having been removed from 55 the pores of the sandston'e, the thin liquid sulfur Will gradually enter and fill the pores ofthe sandstone, Impregnation of the sandstone with the sulfur will generally be complete -Wlti1ll1 from twelve to twenty-four hours, depending upon the size and shape of the object being impregnated. During this sdaking period, it may be found advantageous to occasionally raise the temperature of the bath temporarily as this seems to aid in the impregnation. Vhen particularly. complete impregnation is desired great care-should be paid to the manner of withdrawing the object from the bath. For example, both the bath and the object-should be allowed to cool until, when a surface of the object is lifted from contact with the bath, the sulfur thereon begins to show indications of congealing. Then-the object is slowly withdrawn from the bath and the sulfur on the surface of the object begins to co-ngeal during the op- .eratio In the case of objects of sandstone of relatively large size the simple immersion in the molten sulfur bath may not be suflicient to cause the sulfur to penetrate to the center of the materialand it is necessary to employ a supplemental agency for the purpose of expelling gases from the pores and to drive in the molten sulfur. This may be accomplished by immersing-the sandstone objects in water until they have absorbed water to substantially complete saturation. This sometimes requires a period of twelve hours or more, but may be hastened somewhat by employing hot water. Liquids other than water may be used provided they vaporize at a lower temperature than that at which sulfur melts. Examplesof such liquids are kerosene, or other petroleum oils,

methyl alcohol, carbon tetrachloride, and benzol.

After the objects have been thus completely saturated with water, or other liquid, they are submerged in molten sulfur in the same manner as described above in the case of the impregnation of the dry objects of relatively small size. During this step of the process the water, or other liquid, will be driven off inthe form of steam or vapor. The success of this procedure is attributed to the formation of a partial vacuum within the minute pores and channels of the sandstone, which permits the inflow of the molten sulfur so that the pores become'completely filled.

Another method by which relatively large objects of sandstone may be impregnated with sulfur consists in withdrawing.

the gases. from the pores or interstices in a vacuum chamber and then immersin the objects in molten sulfur before atmosp eric pressure is restored.

When sandstone is to be impregnated for building, architectural, or artistic purposes,

where it is desired to impart a particular color to the sandstone, an appropriate pigment may be mixed with the molten sulfur bath. In this manner the natural appearance of the sandstone may be varied almost at will.

By treating sandstone in accordance with the invention, its properties are improved so as to render it more suitable for itscommon uses because of its "increased strength, increased resistance to corrosion, decomposition and decay and imperviofisness to moisture. Thus, the new productobtained by the practice of the invention is more suitable for building or architecturab purposes because of the general increased strengthening of the sandstone, and its increased .re-

sistance to absorption of moisture and resultlng decomposltlon and decay. Moreover, this new sandstone product is more desirable for such purposes because the im- 3 pregnation of pigments therewith renders it adaptable to improved artistic efi'ects.

Sandstone blocks are frequently employed for the construction of acid towers and other purposes where it is essential that they be very impervious and resistant to the destructive action of various chemicals. Sandstone blocks impregnated with sulfur in accordance with the invention are practically impervious and very much more resistant to the action of acids and alkalis and are, therefore, much more suitable for such purposes than natural untreated sandstone.

Sandstone itself has fair dielectric properties but is objectionable for use as switch boards and the like because of its property of absorbing large quantities of moisture.

I have found that sandstone impregnated with congealed sulfur is excellently suited for use in switchboards and high tension insulators because of the increased dielectric strength imparted by the sulfur congealed in its pores or interstices, and moreover, because sandstone thus treated is practically impervious to moisture.

Pulp stones, grinding stones and the like may be fully or partially impregnated with sulfur in accordance with the invention in order to strengthen them and allow ahigher rate of speed and prevent danger ofbreakage. The advantages of the invention will be further illustrated by the following tests:

Moisture absorption on sandstone before and after sulfur impregnation.

Untreated per cent Treated per cent Specimen. absorption by absorpt on by weight. ,weight.

30 min. 24 hours Averagm; 5102 a 52 0. 01 a Compressive strength of sandstonegbefore and after sulfur impregnation.

Tests on Strength Per cent Per cent treated of un' increase oftreated sSpecimen. specimens treated in strength Unit stone strength to unstrength lb 5 in of treated treated lb. sq in stone. strength.

Average (Stone A)..-" 16,285 9,888 65. 7 165 an- 30,100 Stone B 9, 440 219. 0 319 C 17, 970 4C n: 16,190

Average (Stone o) 17,080 5,162 213.0 331 Results obtained by impregnated pieces of pulp Resulls obtained by impregnating teat cylinders of sandstone.

' Weight Per cent Number cylinder Weight treated Gain 8. s.

Gram Gram I claim: 7

1. The method of improving the properties of sandstone which comprises impreg nating sandstone either wholly or in part with sulfur.

2. The method of improving the properties of sandstone which comprises removin gases from the pores of the sandstone, an impregnating with sulfur the pores thus freed of gases.

3. The method of improving the properties of sandstone which com rises immersing an object of sandstone 1n a bath of molten sulfur, raising the temperature of the sulfurto assist in removin gases from the pores of the sandstone, t ereafter reducing the temperature ofthe sulfur until it becomes a thin liquid, and maintaining the bath in'this state until the sandstone becomesimpregnated with sulfur to the desired extent.

4. Sandstone impregnated with congealed sulfur.

5. Sandstone impregnated with congealed sulfur containing a. pigment, characterized by' increased strength, increased resistance to moisture absorption, and increased resistance to corrosive action.

In testimony whereof I afiix my signature.

WILLIAM HOFFMAN. KOBBE. 

